This application relates generally to injection molding apparatus and more particularly to injection molding apparatus having a cavity insert with a cooling fluid flow channel therein.
Injection molding apparatus having cooling fluid channels or conduits are well known. For instance, the applicant""s U.S. Pat. No. 5,427,519 which issued Jun. 27, 1995 shows a thermal setting application wherein a cooling fluid channel extends around a central liquid molding material channel in a nozzle. The applicant""s U.S. Pat. No. 5,443,381 which issued Aug. 22, 1995 shows hot runner apparatus having cooling fluid conduits extending through a gate insert. Canadian Patent Application Serial Number 2,228,931 filed Feb. 2, 1998 by Mold-Masters Limited is another example of a gate insert having helical cooling fluid conduits or passages.
Accordingly, it is an object of the present invention to at least partially overcome the disadvantages of the prior art by providing a cavity insert with inner and outer portions integrally joined together with a cooling fluid flow channel extending between the inner and outer portions. Also provided is a method to improve the cooling efficiency of a mold cavity to reduce the cycle time.
To this end, in one of its aspects, the invention provides injection molding apparatus having a cavity with an outer surface extending in a mold and a hollow cavity insert having an inner surface mounted in the mold, wherein the inner surface of the cavity insert forms the outer surface of the cavity. The cavity insert has a hollow inner portion and a hollow outer portion integrally joined together. The outer portion has an inner surface and the inner portion has an outer surface. The inner portion fits inside the outer portion with the outer surface of the inner portion adjacent the inner surface of the outer portion. Either the outer surface of the inner portion or the inner surface of the outer portion has a groove therein to form a cooling fluid flow channel extending between the inner portion and the outer portion. The cooling fluid flow channel extends from a cooling fluid inlet to a cooling fluid outlet in a predetermined configuration around the cavity.